This specification covers brick intended for use as the lining in the fireboxes of residential fireplaces. Firebox brick are manufactured from clay, fire clay, shale, or similar naturally occurring earthy substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment must develop a fired bond between the particulate constituents to provide the strength and durability requirements. Firebox brick shall be shaped during manufacture by molding, pressing, or extruding and cutting. Modulus of rupture test, pyrometric cone equivalent test, size test, and warpage test shall be performed to conform to the specified requirements.

1.1 This specification covers brick intended for use as the lining in the fireboxes of residential fireplaces.

1.2 Firebox brick are manufactured from clay, fire clay, shale, or similar naturally occurring earthy substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment must develop a fired bond between the particulate constituents to provide the strength and durability requirements of this specification (see Terminology C1232).

Note 1—Firebox brick are typically installed using ground fire clay mortar or refractory mortar. Mortar joints are typically ¹/₈ in. (3.2 mm) thick, just thick enough to accommodate dimensional variations in the firebox brick.

1.3 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this specification.

1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.